Rust-preventive composition



Patented Nov. 9,

' :1 CQMPOQI'HON George Hugo von Fuolis and Norman 8. Wilson,

Alton, 311., assignors to Shell Development Company, San Francisco. Calif., a corporation Delaware No Drawing.

Applloationieptembcr 2c, 1w, Serial No. 412.838

1: Claims. (01. sea-rs) This invention relates to anti-corrosive hydrocarbon compositions such as gasolines, Diesel fuel oils, lubricating oils, flushing oils, albino asphalt coatings, etc., and more particularly deals with hydrocarbon oils containing dissolved small amounts of certain corrosion inhibitors together with an organic solvent, which is at least partially miscible with water and preferably is capable of dissolving lubricating oil sludges.

It is the purpose of this invention to produce proved corrosion protective, and particularly antirust properties. -It is another purpose to produce lubricating oils of improved anti-corrosion properties. Another purpose is to produce a flushing oil'having a high capacity for removing oil sludges and other products of deterioration formed during lubrication of machinery. More particularly, it is a purpose to produce a highly effective flushing oil for steam turbines.

It is known that relatively high molecular weight .polycarboxylic acids, as well as certain hydroxy carboxylic acids, when dissolved in hydrocarbon oils in small quantities, have the property of causing the blended oil to become anticorrosive and capable of positively protecting acids such as alkylated succinic, glutaric, adipic,

pimelic, suberic, azelaic, tricarballylic, citric, etc., acids, alkylated oxy-benzoic acids such as methyl metaand para-oxy-benzoic acids, di-isopropyl salicylic acid, etc., acids. If desired these acids might contain various substitution radicals such as hydroxyl, ether, amino, nitro, hydrosulfide, sulfide, halide, etc., radicals.

The saturated acids are preferred because of their greater stability toward oxidation resulting in protective layers which have longer active life.

The most'useful dicarboxylic acids for our purposes are alkylated succinic acids having more than 16 carbon atoms and preferably those having a total of 20 or more carbon atoms. We limit the molecular size of our acids because the polyhydrocarbon oils and plastic compositions of improperties. Suitable acids may be produced by reacting oleflns boiling above about 300 e., such as may be obtained by cracking paraflin wax or by dehydration of long chain fatty alcohols, etc., with maleic acid anhydride to produce an alkylene succinic anhydride, hydrogenating to produce the alkyl succinic acid anhydride and hydrolyzing the anhydride to produce the corresponding free acid. Such acids have been described mu. 3. Patent No. 2,133,734.

It is known that lubricating oils may, and usually do, form sludges upon prolonged use. These sludges tend to deposit on metal surfaces, thereby interfering with proper lubrication. It is, therefore, necessary to remove such sludges, which may have deposited, by suitable means, as by flushing.

Due to their polar nature, sludges tend to absorb water, thus becoming hydrated, and while in this state they are practically insoluble in hydrocarbon oils which are normally employed for flushing. Therefore, it is often dimcult successfully to remove deposited oil sludges from machinery by simple flushing.

Moreover, sludge deposition frequently coincides with corrosion, e. g., rusting, and it is not uncommon that when deposited sludges have finally 'been removed a certain amount of more or less loose rust is left which may cause rapid deterioration of fresh lubricating oils, and under unfavorable conditions may interfere with oil circulation, thereby endangering the entire machinery.

Now we have discovered that the above difflculties can be overcome, i. e., metal parts can positively and efiectively be protected against corrosion, without having to depend upon accidental thorough admixture with water; or sludges, hydrated or not, deposited in machinery together with at least a portion of rust which may have formed, can be removed effectively by flushing, by using a hydrocarbon composition comprising predominantly non-gaseous hydrocarbons containing a minor proportion of a substantially neutral mutual solvent for hydrocarbons and water, and a relatively small amount of a high molecular weight polycarboxylic acid known to possess corrosion inhibiting properties.

Due to the presence of the mutual solvent, the

hydrocarbon compositions of our invention are carboxylic acids of less than 16 carbon atoms are capable of dissolving at least small amounts of known to have little or no corrosion water, sothat the polycarboxylic acids can react to form the protective coatings onmetals with' out the need for agitation in the presence of a separate water layer.

No protective film forms on ferrous metals immersed in oil containing the corrosion preventive polycarboxylicor hydroxycarboxylic acids, even after immersion with prolonged agitation or circulation, provided that the oil is dry and no free water or other polar material is present. Diffusion alone apparently cannot provide the active components necessary for film formation as long as the equilibrium is not disturbed by local depletion of the anti-corrosive, due to attraction toward and, chemical reaction with a polar interface. Water and other polar substances provide such an interface by absorption in the hy; groscopic uni-molecular oxide film present even on freshly polished ferrous metal surfaces.

The action of water and of other suitable polar compounds is thus two-fold: l. e., they provide a polar interface and they ionize the carboxyl group of the polycarboxylic acids, thus facilitating the formation of av water-repellent, lyophilic but essentially oil-insoluble soap with the oxide film attached to the metal surface.

While water thus indirectly promotes diffusion, for oils containing only small amounts of the polycarboxylic acids, circulation is helpful, even in the presence of a polar compound, since in the immediate vicinity of the metal surface, the number of active molecules is usually insufilcient to form a continuous protective film rapidly.

Under many circumstances it may be desirable to introduce into our compositions small amounts of water, say about .05% to 1%, from the verystart. The reasons for this may be explained most readily by way of consideration of some examples.

Take, for instance, a gasoline that is to be stored in drums in a tropical climate. It is a well-known phenomenon that upon prolonged storage under these conditions, several inches of water may accumulate with the result that heavy rusting of the drums occurs. If the gasoline contains some of the polycarboxylic acids, this corrosion is effectively prevented if the drums are kept moving until such time as is required to form the protective film. Depending upon various circumstances, this time may be of the order of several days or even weeks. If however, the gasoline contains dissolved at small amount of water, this time may be reduced to the order of a fraction of a second.

The amounts of the several components in our compositions and the exact nature of the mutual solvents depend to some extent upon the use for which the compositions. are intended. Hydrocarbon fuels. such as gasoline, require only a small quantity of the polycarboxylic acids and a relatively small quantity of solvent boiling within the boiling range of the particular fuel. Thus a gasoline fuel may be composed of 95% to over 99% gasoline, .001% to .l% of a polycarboxylic acid and .l% to 5% of a solvent such as dialkyl ethers, e. g. di-isopropyl ether. methyl tertiary butyl ether, ethyl tertiary butyl ether, isopropyl tertiary butyl ether, methyl tertiary amyl ether, dioxan'e, etc.; alcohols boiling within the gasoline range such as ethyl alcohol, propyl alcohol, isopropyl alcohol. lsobutyl alcohol, tertiary butyl alcohol. tertiary amyl alcohol, etc.;= ketones boiling within the gasoline range such as methyl ethyl ketone, acetone, diethyl lretone, di-isobutyl ketone, etc. Some of these solvents may be present in sufilcient quantities also to raise the octane rating of the fuel. Larger amounts of the inhibitor are apt to result in high A. B. T. M. glass 6 Diesel fuels also require relatively small amounts only of polycarboxylic acids and solvents. 'l'hese fuels, like gasolines, should contain .001% to .l% of the inhibitor and .l% to 5% of a solvent, preferably one tending to improve oetane numl bers such as nitro-paramns, e. g. nitro ethane, nitropropane, nitrobutane, nitro pentane, C1-C0 nitrates or nitrites, nitro mercaptans of 2 to 5 carbon atoms, various peroxides as peroxides of aliphatic ketones having say 3 to 8 carbon atom, benzoyl peroxide, diacetyl peroxide, tetraline peroxide, etc. However, other solvents not materially affecting cetane numbers may be used, such as ketone, e. g. acetone, methyl ethyl ketone, diethyl ketone, glyoxal, or alcohols such as ethyl alcohol, propyl alcohol, amyl alcohol, etc.: ethers such as diethyl ether, dipropyl ether, ethyl namyl ether, dioxane, ethylene glycol mono alkyl ethers, esters such as ethyl acetate, methyl propionate, etc. 26 Lubricating oils may require, though not necessarily, larger quantities of both polycarboxylic acids and solvents than fuels because normally they are subjected during use to heat while being intimately mixed with air, which conditions are 80 conducive to the formation of both soluble corrosive products and insoluble sludge. Considerable variation in the composition of a lubricating oil is permissible. Thus our lubricating oils may be composed of 80% to 99+% of a lube oil,

'86 .001% to 1.0% of a polycarboxylic acid and .l%

to 20% of a suitable solvent, although for ordinary engine lubrication we usually prefer to limit the solvent to below 5% by weight. While many solvents are operative, we prefer for practical 40 reasons to limit solvents used in lubricating oils to those boiling above about 150 C. Solvents in this category are alcohols, such diols having 6 or more carbon atoms, as hexylene glycols, decylene glycols, cetylene glycols, etc.; diglycols such as dipropylene glycol,dibutylene glycol, di-amylene glycols; triglycols such as tripropylene glycol; ether alcohols preferably containing not more than 2 OH'radicals, more particularly glycol mono alkyl ethers, e. g., the cellosolves such as ethylene glycol mono ethyl ether, ethylene glycol mono propyl ether, ethylene glycol mono n-butyl ether, ethylene glycol mono iso butyl ether, ethylene glycol mono tertiary butyl ether, ethylene glycol mono hexyl ether, etc.; p opylene glycol mono ethyl ether, propylene glycol mono isoamyl ether, etc.; diglycol monoalkyl ethers, for example, the carbitols such as diethylene glycol mono methyl ethyl nethylene glycol mono butyl ethers, diethylene glycol mono decyl ethers, etc glycol mono ethyl ether, dipropylene glycol mono isopropyl ether, dipropylene glycol mono isoamyl ether, dipropylene glycol mono heptyl ether, diisobutylene glycol mono isopropyl ether, ethylenepropylene glycol mono ethyl ether, ethyleneisobutylene glycol mono isopropyl ether, etc.; also glycerine mono-.or di-ethers of 6 or more carbon atoms, such as glycerine monoor di-propyl butyl, amyl, etc. ethers; mono e glycerine, etc.

Our flushing oil compositions normally require amounts between about '.01% and .25 of polycarboxylic acid, and about 2% to 20% of solvent. The hydrocarbon oils which we prefer to use in 75 the flushing oil may consist of relatively high and isopropyl ethers, di-

.; also dipropylene sters of glycol or asserts boiling fractions, e. g. gas oil fractions of coking cycle stocks obtained by operating a liquid phase cracking unit under conditions to produce coke instead of residual fuel oil, or of so-called blow vapor phase, cracked, or other high boiling distillates provided they are sufliciently aromatic. e. g. preferably containing at least 50% aromatics and preferably having specific dispersions above about 200 as determined by the method of Von Fuchs and Anderson (Ind. Eng. Chem. 29, 819 March, 1937). For safety's sake, relatively high flash and fire points are desirable.

The solvents useful in the flushing oils are the same as those mentioned above as useful in the lubricating oil composition.

In general, our flushing oil compositions do not require the presence of added water to activate the inhibitor.

Oil sludges formed by the deterioration of the 011, e. g. by oxidation, are usually hydrated. The mutual solvent desiccates the sludge, taking up water and thereby not only rendering the sludge soluble in the aromatic hydrocarbon oil, but also activating the'polycarboxylic acid. Moreover, in certain types of machinery such as steam turbines, water frequently accumulates in the lubricating system through condensation of water vapor. When draining the oil, at least a portion of this water may remain in pockets, and when flushing the crankcase this water is admixed with the flushing oil, thereby activating the inhibitor.

To make these aromatic fractions more effective for flushing oil, olefins, particularly dioleficien't to homogenize the small amount of water necessary to readily activate the inhibitor. Thus, the solvent may vary from .1% to 90%.

Our corrosion inhibiting compositions may, if desired, contain other addition agents to correct some property other than corrosion resistance,'in which the composition is totally or partially deficient. Thus, for example, our gasoline compositions may, in addition, contain anti-knock compounds and conventional antioxidants; our Diesel fuels may contain knock suppressors and antioxidants; our lubricating oil compositions may contain antioxidants, blooming agents. E. P. compounds, detergents, etc.

Our invention is more fully set forth in the following examples: V

Example I A blow down oil from a cracking unit was treated with 25 lbs. of 98% HsSOs/bbl. of oil. After the oil was separated from the acid and contacted with a clay, it was vacuum distilled to yield a so-called neutral oil constituting about 80% of the original treated oil. This neutral oil was used to prepare a flushing oil comprising about 95% by weight of neutral oil, about by weight of (ii-ethylene glycol mono-butyl ether and 0.01% of an alkyl succinic acid containing 22 carbon atoms. This composition was circulated through the lubrication system of a steam turbine, which was badly sludged. for 30 minutes. The flushing oil, which was then drained out, carried with it substantially all of the sludge and alarm amount of rust.

5 The flushing oil collected in'pockets and, clinging to the walls, wasremoved by a displacement oil. The lubricating system was filled with turbine oil and an analysis made of samples from the oil reservoir after a short period of operation.

The oil showed only slight contamination.

Example II A flushing oil having thesame composition as the oil of Example I was used to clean the oil reservoir built in the bottom of the gear case of a geared turbo-generator. The flushing oil was recirculated to and from the gear-case oil reservoir through an auxiliary pump, filter screen and steam heater. The turbine cleaner was drained from the case and the last or the cleaner removed by a displacement oil. The gear-case was charged with fresh lubricant and the turbogenerator was again placed in service.

The cleaning was so complete that the final oil charge did not change its interfacial tension toward water over many hours of operation indicating the absence of oil soluble impurities.

We claim as our invention: 1. An anti-corrosive composition of matter 80 comprising predominantly non-gaseous hydrocarbons containing small amounts each of a polycarboxylic acid having at least 16 carbon atoms and of a mutual solvent for hydrocarbons and water.

2. An anti-corrosive composition of matter comprising predominantly a refined mineral 011 containing from .001% to .1% of a polycarboxylic acid having at least 16 carbon atoms and .1 to 5% of a mutual solvent for hydrocarbons and water.

3. The composition of claim 1 in which the mtifitual solvent is a di-ethylene glycol mono alkyl e er.

4. The composition of claim 1 in which the mutual solvent is an ethylene glycol mono alkyl ether.

5. The composition of claim 1 in which the polycarboxylic acid is an alkyl succinic acid.

6. The composition of claim 1 in which the.

polycarboxylic acid contains a substitution radical selected from the group consisting of hydroxyl, ether, amino, nitro, hydrosulflde, sulfide, halide radicals.

'7. An anti-corrosive composition of matter comprising predominantly a refined mineral lubricating oil and small amounts each of a polycarboxylic acid having at least 16 carbon atoms and of a mutual solvent for hydrocarbons and water boiling above 150 C. I

8. An anti-corrosive composition of matter comprising predominantly a refined mineral lubricating oil containing .001% to 1.0% of a polycarboxylic acid of at least 16 carbon atoms and .1% to 20% of a mutual solvent for oil and water boiling above 150 C.

9. An. anti-corrosive composition of matter comprising predominantly a Diesel grade fuel oil containing ..001% to '1% of a polycarboxylic acid of at least 16 carbon atoms and .1% to 5% of a mutual solvent for hydrocarbons and water.

10. An anti-corrosive composition of matter comprising predominantly a hydrocarbon fuel,

boiling in the gasoline range, containing .001% p to 1% of a polycarboxylic acid of at least 16 carbon atoms and .1% to 5% of a mutual solvent 7 for hydrocarbons and water.

11. An anti-corrosive composition or matter comprisin predominantly a hydrocarbon fuel, boiling in the gasoline range, containing .001% to 1% or a polycarboxylic acid of at least 16 carbon atoms and .1% to 5% or a mutual solvent for hydrocarbons and water having anuknock properties,

12. A flushing 011 comprising oredominantly a refined highly aromatic cracked hydrocarbon oil and small amounts each of a polycarboxylic acid GEORGE HUGO von FUCHS. NORMAN B. WILSON. 

